Guide: Render typst math in MkDocs

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Introduction

MkDocs is an open source Python static site generator focused for Markdown, and Material for MkDocs is a popular theme. This ecosystem is very popular, e.g., arXiv help pages uses it.

It is possible write LaTeX math in *.md, and let MathJax/KaTeX render formulae in the browser. See Arithmatex - PyMdown Extensions Documentation for more info.

However, once you have written $cal(T): {e_n}_n -> CC$, it is hard to write $\mathcal{T}: \{e_n\}_n \to \mathbb{C}$ again…

Result

  • Render typst math at the build time.

    图片

    <!-- Source markdown -->

用压缩映射原理分析关于 $phi$ 的积分方程

$$
phi (x) equiv f(x) + integral K(x,y) phi(y) dif y
$$

的解的存在性，其中 $abs(K)$ 有上界 $M$。

  • Integrate into the MkDocs site: dark theme, site search, permalink, admonitions, back-to-top button, …

    图片

  • Coexist with LaTeX math. You can write typst math on some pages and write LaTeX math on other pages.

  • Faster loading time than MathJax.

  • Minimum hack.

    The most hacky part is the CSS style to make formulae copiable, but that’s quite common in the front-end world.

However, I just finished it yesterday. Use it at your own risk.
I will iterate and test, and publish it to PyPI under MIT License when appropirate.

How to render typst math in MkDocs

  1. Edit mkdocs.yml and add the following.

    markdown_extensions:
  - pymdownx.arithmatex:
      generic: true

hooks:
  - hooks/typst_math.py

extra_css:
  - stylesheets/extra.css

  2. Save the following to docs/stylesheets/extra.css.

    .typst-math > svg {
    overflow: visible;
}
div.typst-math {
    display: flex;
    justify-content: center;
}

/*
    https://v3.tailwindcss.com/docs/screen-readers
    will interrupt the selection, thus unusable
*/
.sr-only {
    position: absolute;
    left: -9999px;
}

  3. Save the following to hooks/typst_math.py

    """Render math with typst

## Usage

1. Install the markdown extensions pymdownx.arithmatex.
2. Add `math: typst` to pages' metadata.

## Requirements

- typst

"""

from __future__ import annotations

import html
import re
from functools import cache
from subprocess import CalledProcessError, run
from typing import TYPE_CHECKING

if TYPE_CHECKING:
    from mkdocs.config.defaults import MkDocsConfig
    from mkdocs.structure.files import Files
    from mkdocs.structure.pages import Page


def should_render(page: Page) -> bool:
    return page.meta.get("math") == "typst"


def on_page_markdown(
    markdown: str, page: Page, config: MkDocsConfig, files: Files
) -> str | None:
    if should_render(page):
        assert "pymdownx.arithmatex" in config.markdown_extensions, (
            "Missing pymdownx.arithmatex in config.markdown_extensions. "
            "Setting `math: typst` requires it to parse markdown."
        )


def on_post_page(output: str, page: Page, config: MkDocsConfig) -> str | None:
    if should_render(page):
        output = re.sub(
            r'<span class="arithmatex">(.+?)</span>', render_inline_math, output
        )

        output = re.sub(
            r'<div class="arithmatex">(.+?)</div>',
            render_block_math,
            output,
            flags=re.MULTILINE | re.DOTALL,
        )
        return output


def render_inline_math(match: re.Match[str]) -> str:
    src = html.unescape(match.group(1)).removeprefix(R"\(").removesuffix(R"\)").strip()
    typ = f"${src}$"
    return (
        '<span class="typst-math">'
        + fix_svg(typst_compile(typ))
        + for_screen_reader(typ)
        + "</span>"
    )


def render_block_math(match: re.Match[str]) -> str:
    src = html.unescape(match.group(1)).removeprefix(R"\[").removesuffix(R"\]").strip()
    typ = f"$ {src} $"
    return (
        '<div class="typst-math">'
        + fix_svg(typst_compile(typ))
        + for_screen_reader(typ)
        + "</div>"
    )


def for_screen_reader(typ: str) -> str:
    return f'<span class="sr-only">{html.escape(typ)}</span>'


def fix_svg(svg: bytes) -> str:
    """Fix the compiled SVG to be embedded in HTML

    - Strip trailing spaces
    - Support dark theme
    """
    return re.sub(
        r' (fill|stroke)="#000000"',
        r' \1="var(--md-typeset-color)"',
        svg.decode().strip(),
    )


@cache
def typst_compile(
    typ: str,
    *,
    prelude="#set page(width: auto, height: auto, margin: 0pt, fill: none)\n",
    format="svg",
) -> bytes:
    """Compile a Typst document

    https://github.com/marimo-team/marimo/discussions/2441
    """
    try:
        return run(
            ["typst", "compile", "-", "-", "--format", format],
            input=(prelude + typ).encode(),
            check=True,
            capture_output=True,
        ).stdout
    except CalledProcessError as err:
        raise RuntimeError(
            f"""
Failed to render a typst math:

```typst
{typ}
```

{err.stderr.decode()}
""".strip()
        )

  4. Start writing.

    ---
math: typst
---

# Heading

Inline math: $phi$.

Block math:

$$
phi (x) equiv f(x) + integral K(x,y) phi(y) dif y
$$
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